Calcium dependency of potassium-stimulated thyrotropin-releasing hormone secretion from rat neurohypophysis in vitro.
The role of Ca2+ on the K+ -stimulated release of thyrotropin-releasing hormone (TRH) from rat neurohypophysis, stalk median eminence (SME) and hypothalamic fragments in vitro was studied. High K+ (50 mM) caused a significant increase (2-6-fold) in TRH release from all three tissues, (P less than 0.05-0.01), and this effect was inhibited (by 62-80%) on removing Ca2+ (1.8 mM) from the medium (P less than 0.01). The calcium dependency of the TRH response to a membrane depolarizing stimulus (high K+) is consistent with TRH release occurring by a neurosecretory process from the neurophypophysis, as well as from hypothalamic tissue.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008473:Median Eminence / Q000187:drug effects / Q000378:metabolism; D010904:Pituitary Gland, Posterior / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
D013973:Thyrotropin-Releasing Hormone; D011188:Potassium; D002118:Calcium